Retrotechtacular: Mechanical Targeting Computers


The device that these seamen are standing around is a US Navy targeting computer. It doesn’t use electricity, but relies on mechanical computing to adjust trajectories of the ship’s guns. Setting up to twenty-five different attributes by turning cranks and other input mechanisms lets the computer automatically calculate the gun settings necessary to hit a target. These parameters include speed and heading of both the ship and it’s target, wind speed and bearing, and the location of the target in relation to this ship. It boggles the mind to think of the complexity that went into this computer.

The first of this seven part series can be seen after the break. The collection covers shafts,  gears, cams, and differentials. Sounds like it would be quite boring to sit through, huh? But as we’ve come to expect from this style and vintage of training film it packs a remarkable number of simple demonstrations into the footage.

See all seven parts of the series

[Thanks Justin]

26 thoughts on “Retrotechtacular: Mechanical Targeting Computers

    1. Yep, my brother is an engineer and some of the biggest defense contractors call him for advice, but his spelling and punctuation are sadly less than academic. It’s its own tragedy, isn’t it?

  1. We still use humans for a lot of this work but now they function as back ups to the automated targeting systems. As an Operation Specialist in the USCG we still do call outs down in combat and controll for range, bearing, distance, rate of closure, and closest point of approach to plotters on paper charts for navigation. Our Electronic Techs (who absorbed the Fire control Techs) are still trained to do all the targeting on a Maneuvering Boards (MoBoard) if necessary. The only data they don’t calculate on the MoBoard is elevation, which I’m sure they have tables for.

    The human factor now-a-days is mostly for accountability and preventing “friendly fire”. Politicians want to be able to point a finger at another human and say “its your fault!” Currently the only fully automated “gun” systems are defensive in nature. The CIWS and SRBOC, though the newer versions of the CWIS can be target designated. However the CWIS’s complexity has changed the weapons acronym from Close In Weapons System to Christ It Won’t Shoot. Half the components are dedicated to re-linking the spent shell casings.

      1. They probably re-link them so they’ll fit in the space they have to go in. A bunch of jumbled objects is not optimally packed. But I’d hate to have my ship sunk because the damn auto-turret wasn’t shooting at the enemy due to a spent casing jamming up the works.

        Getting back on topic, these films are terrific introductions into applied trigonometry. Completely worth watching the whole series.

    1. Close In Weapon System
      After a round is fired it is belt fed back into the drum until the system is reloaded. Then, a loader is placed onto the front of the drum to unload the spent casings and replace with more live ammo or the dummy rounds (they are used to cycle the gun and provides a counter balance). The rounds come in a typical machine gun style belt with an added metal shroud over the primer. This shroud is designed to prevent the round from being set off by radiation. The electrical primer of the round only requires 25 volts dc to fire.

      Additional Information.
      Weapon Type: Defense
      Gun Caliber: 20mm
      Number of Barrels: 6
      Round: Spin stabilized depleted uranium (one of the densest metals)
      Initial Velocity: 3800 fps
      Rounds per Minute: 3000/4500 last 2 seconds of burst
      Will engage Targets that are inbound and moving in excess of 148 knots

    1. During an overnighter with my scout troop on the USS Missouri, got a look at the fire control computer. A thing of beauty. Unfortunately, I was still using film, and when we got to the computer, I was out.

    1. When I first went into the Ohio National Guard in the late 1980s we had the M-42 Dusters, which was an amazing dual 40mm ack ack style gun with turrets from decommissioned WWII navy ships. They had a similar 2 person manual computer to direct the firing. I don’t think anyone in the unit really knew how to use the mechanical computer. They were all replaced with more modern missile based systems in the early 1990s.

  2. I remember when I first came across these videos, they blew my mind. They were my first true taste of calculus, and although I couldn’t fully appreciate it at the time, the intuition for the mathematics of the natural world that I gained therefrom – that is truly priceless :)

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